High-precision systems are useful for precisely and accurately positioning workpieces and/or tools using a movable platform or stage. For example, high-precision platforms are used in manufacturing and inspection systems in which precise movements are necessary for positioning a workpiece. Examples of such high-precision systems are microlithography systems that utilize a movable stage assembly for holding and controllably moving a lithographic substrate relative to an imaging optical system. Stage motions are typically effected using linear motors or planar motors in which a coil array interacts with a magnet array to produce motion of the stage relative to the base. Such motors can be cooled to cryogenic temperatures to reduce the resistance in the coils, thereby reducing heat generation in the precision system. However, this can affect the time constant of the coils and, consequently, the stability margin of the system, the current amplitude response, and the force output of the coils. Accordingly, improved devices and methods of controlling current in cryogenically cooled motors are desirable.
Utilities such as power, vacuum, water, etc., are typically supplied to a wafer stage by one or more cables and/or hoses pendantly extending from the wafer stage to a frame body of the precision system. Such cables and hoses impart disturbances on the wafer stage, which can negatively impact the precision and accuracy of stage movements. Accordingly, improved devices and methods of reducing the disturbances imparted to the stage by pendant cables and hoses is also desirable.